Brain and nerve = Shinkei kenkyū no shinpo
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Detection of unmyelinated epidermal nerve fibers allows objective, pathologic, and minimally invasive assessment of small myelinated A-delta and unmyelinated C primary afferent fibers. This procedure is especially valuable for diagnosing small fiber neuropathy; this condition is characterized by sensory symptoms and pain in the lower extremities but standard nerve conduction fails to show abnormalities in this condition. ⋯ In this review, we discuss standard technical aspects of skin biopsy introduced for evaluation of epidermal nerve fibers and the feasibility of skin biopsy for diagnosing small fiber neuropathy and neuronopathy. We also describe the usefulness of skin biopsy in diagnosing peripheral neuropathies and other neurological disorders.
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Review
[Pharmacological treatment strategy and mirror visual feedback treatment for neuropathic pain].
Neuropathic pain is a debilitating condition, and pharmacotherapy is the most established treatment strategy. A variety of pharmacotherapies is used for neuropathic pain management: however, pharmacotherapies with evidence for analgesic potency are less common. ⋯ We have treated pharmacotherapy-resistant neuropathic pain with neurorehabilitation techniques such as mirror visual feedback (MVF) treatment. Further to our clinical experience using MVF, we discuss the cerebral mechanism associated with neuropathic pain in this study.
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Neuropathic pain syndromes are clinically characterized by spontaneous pain and evoked pain (hyperalgesia and allodynia). The optimal treatment approach for neuropathic pain is still under development because of the complex pathological mechanisms underlying this type of pain. ⋯ Central sensitization represents enhancement of the function of neuronal circuits in nociceptive pathways and is a manifestation of the remarkable plasticity of the somatosensory nervous system after nerve injury. This review highlights the pathological features of central sensitization, which develops because of (1) injury-induced abnormal inputs from primary afferents, (2) increase in the excitability of dorsal horn neurons, and (3) activated glial cell-derived signals.
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Evidence regarding the effectiveness of nerve block in treating neuropathic pain is scarce. However, in actual clinical situations, nerve block has been used as a treatment in combination with other methods, such as pharmacotherapy, psychotherapy, and physiotherapy. The goal of neuropathic pain treatment is not a complete recovery but some improvement in the activities of daily living (ADL) as well as the quality of life. ⋯ Therefore, the use of nerve block should be considered from the onset of pain. In recent years, methods such as ultrasound-guided nerve block and thermocoagulation with pulsed radiofrequency have become more commonly used as safer and more accurate nerve block techniques. This article discusses the current clinical status of nerve block against neuropathic pain.
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Pain is classified into physical and psychological pain. Physical pain is nociceptive, inflammatory, or neuropathic. Pain can be categorized into acute or chronic pain depending on the duration of pain and mechanism of onset. ⋯ Chronic pain is caused by incurable conditions or requires a long time to heal and is persistent: it includes chronic nociceptive pain, established neuropathic pain, and psychogenic pain. The therapeutic strategies for pain depend on the underlying pathological conditions: (1) For nociceptive pain, analgesics, narcotic analgesics, and nerve block are indicated. (2) For neuropathic pain, supplementary analgesics, but not analgesics, are indicated, and some narcotic analgesics are also effective: the recommended supplementary analgesics include calcium channel alpha-2-delta ligands, tricyclic antidepressants (TCAs), and serotonin-noradrenaline reuptake inhibitors (SNRIs). (3) For psychogenic pain, analgesics and nerve block are not indicated, except in the setting of a placebo effect: in paticular, narcotic analgesics should not be used. Psychological therapy, tranquilizer administration, cognitive behavior therapy, and patient education are indicated for this kind of pain.